In Scislowicz U.S. Pat. No. 3,216,418, a burette-type administration set is described having a burette chamber with a bottom flow aperture and a float-type valve controlling flow through the aperture. The purpose of this type of structure is to prevent the further draining of the set when the burette chamber is empty, so that air is not placed into the lower portion of the administration set, with the consequent danger that upon the refilling of the burette chamber the weight of the solution might drive air bubbles through the set into the patient.
Problems, however, have arisen with hinged float and floating disc-type valves, as shown in this patent, in that they occasionally fail to perform the function for which they are intended, with the structures utilized in the patent becoming "hung-up", and failing to properly close. In the absence of a proper closure, upon emptying of the burette chamber, air continues to pass through the bottom aperture of the chamber, which in turn permits the liquid level of the set to drop. When this happens, if noticed, the set must be removed from the patient and reprimed. If not noticed, the patient is in danger of receiving air along with the parenteral solution, which can be life-threatening in serious situations.
Also, a similar device is sold in which the valve at the bottom aperture of the burette set is a porous, hydrophilic membrane. This valve has no moving parts to get out of order, and thus can be extremely reliable. However, some medicaments which would be desirably added to the burette chamber, and are of low solubility, may be undesirably filtered out and clog the filter membrane valve. Also, it has been found that the device requires a small amount of extra training to learn how to use it properly. Untrained people have been found, on occasion, to break the membrane valve during their attempted priming of the set, which of course largely inactivates the membrane valve.
It has been found that the device of this invention, being a floating ball valve, is more easily utilized by inadequately trained personnel, since there is no membrane to break. Accordingly, there is also no problem of clogging of the membrane due to various supplemental medications that desirably might be added to the burette chamber.
Furthermore, the parenteral liquid administering device of this invention has been found to exhibit greater reliability in its valve closure characteristics than flap valves and the like, resulting in fewer failures of the product. This in turn greatly reduces the risk that a patient may be subjected to an air embolism, as well as eliminating the necessity to remove defective sets from use and to replace them with a new set, making a new venopuncture in the patient's arm.